Remove (almost) all remaining instances of PLATFORM().

I added FIXMEs and filed a bug for the two instances that remain.

BUG=none

Review URL: https://codereview.chromium.org/14121014

git-svn-id: svn://svn.chromium.org/blink/trunk@148304 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Override run-webkit-tests with new-run-webkit-tests

The old script isn't needed anymore and was making us support
non Chromium platforms. This means that run-webkit-tests now
defaults to automatically to --chromium!

We cannot remove new-run-webkit-tests as it is required by the
build bots. Once this change rolls into to DEPS, we can safely
land codereview.chromium.org/13980005 and remove the file.

BUG=

Review URL: https://codereview.chromium.org/13975015

git-svn-id: svn://svn.chromium.org/blink/trunk@148305 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove ACCELERATED_2D_CANVAS define

Keeping the code as if ACCELERATED_2D_CANVAS were enabled.

BUG=230224

Review URL: https://chromiumcodereview.appspot.com/14208002

git-svn-id: svn://svn.chromium.org/blink/trunk@148306 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove all references to webkit_test_runner in Blink

webkit_test_runner was used by WebKit2 which we don't support. Also
removed the tests that were specific to WebKit2 and started failing
after this change.

BUG=

Review URL: https://codereview.chromium.org/14214002

git-svn-id: svn://svn.chromium.org/blink/trunk@148307 bbb929c8-8fbe-4397-9dbb-9b2b20218538